Finkelstein Reaction:
The Finkelstein reaction is named after
the German chemist Hans Finkelstein. In
this reaction, one halogen atom exchanges for another. It is basically single-step
bimolecular nucleophilic substitution reaction (SN2 reaction).
According to classic Finkelstein
reaction an alkyl chloride or an alkyl bromide is converted into alkyl iodide by
the treatment with a solution of sodium iodide in acetone.
Sodium iodide is soluble in the
acetone but sodium chloride and sodium bromide are not. So when sodium chloride
or sodium bromide are formed in the reaction, it get precipitated and this help
reaction to driven to completion due to mass action.
For
example, bromoethane can be converted to iodoethane:
Every alkyl halide reacts
differently when it undergoes the Finkelstein reaction. The reaction works well
for primary (except for neopentyl)
halides, and exceptionally well for allyl, benzyl, and α-carbonyl halides.
Secondary halides are far less reactive. Vinyl, aryl and
tertiary alkyl halides are unreactive.
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